Field-based nutritional response evaluation of the intolerant white lupin (Lupinus albus) cultivar Lucyanne to a lime-amended soil

Abstract

Two field experiments examined the nutritional responses of the white lupin (Lupinus albus L.) agronomic cultivar Lucyanne to lime-amended soil. In the first, plots and boundaries of a pre-existing lime-rate experiment were sampled in 1993. The maximum shoot dry matter production occurred between soil pH 4·9 and 7·2. Whole-shoot Al concentrations increased below soil pH 4·9, and plants died at pH 4·4. Although dry matter production declined in soil above pH 7·2, no chlorosis or plant death was seen. Only the whole-shoot soluble Ca concentration changed from neutral to alkaline pH soil: it was greatest when grown in the alkaline-pH soil. In the second experiment, plants were grown in neutral pH or limed soil in 2000. Shoots were divided into specific tissue types and analysed for Fe III and Fe II, as well as soluble and insoluble Ca fractions. When sampled in April after over-wintering, the higher Ca concentration in the limed compared with neutral-pH soil-grown plants was due mainly to insoluble Ca. No plants were chlorotic and no differences between the treatments in the concentrations of either form of Fe were found. In June no plants were chlorotic, however the concentrations of both total and soluble Ca fractions were greater in the limed than the neutral-pH soil-grown plants, and there was more stem Fe III and less leaf Fe II in these plants. The present study shows that the cultivar Lucyanne is not a reliable crop plant above pH 7·2, and the loss of shoot dry matter can be attributed to nutritional responses at a sub-chlorotic level of stress.